You can download the latest DLLs here:
https://github.com/IndySockets/OpenSSL-Binaries
and for more info go here:
https://docwiki.embarcadero.com/RADStudio/Sydney/en/Securing_Indy_Network_Connections
I would change:
SSLOptions.Method := sslvTLSv1;
to
SSLOptions.Method := sslvTLSv1_2;